class_docstr: 存在多个auto_collate和多个collate_fn时候，对一个批次数据集应用哪个auto_collate和collate_fn的问题
class_docstr_tok: ["\u5b58\u5728\u591a\u4e2aauto_collate\u548c\u591a\u4e2acollate_fn\u65f6\u5019\uff0c\u5bf9\u4e00\u4e2a\u6279\u6b21\u6570\u636e\u96c6\u5e94\u7528\u54ea\u4e2aauto_collate\u548ccollate_fn\u7684\u95ee\u9898"]
docstr: 调用一次该方法，我们将ins_list视为同一个数据集采样出来的，故ds_index只能为一种
  
  :param ins_list:
  :return:
docstr_tok: ["\u8c03\u7528\u4e00\u6b21\u8be5\u65b9\u6cd5\uff0c\u6211\u4eec\u5c06ins_list\u89c6\u4e3a\u540c\u4e00\u4e2a\u6570\u636e\u96c6\u91c7\u6837\u51fa\u6765\u7684\uff0c\u6545ds_index\u53ea\u80fd\u4e3a\u4e00\u79cd",":","param","ins_list",":",":","return",":"]
code: def __call__(self, ins_list: List) -> Dict:
      """
      调用一次该方法，我们将ins_list视为同一个数据集采样出来的，故ds_index只能为一种
  
      :param ins_list:
      :return:
      """
      _ins_list, _ds_index = [], 0
      for ins, _ds_index in ins_list:
          _ins_list.append(ins)
      _ins_list = self.collate_fns(_ds_index, _ins_list)
      return _ins_list
  
file_path: fastNLP/fastNLP/core/dataloaders/torch_dataloader/mix_dataloader.py
imports: from typing import Optional, Callable, List, Union, Tuple, Dict, Sequence, Mapping
  import numpy
  from pkg_resources import parse_version
  from fastNLP.core.dataset import DataSet, Instance
  from fastNLP.core.samplers import PollingSampler, MixSequentialSampler, DopedSampler
  from fastNLP.envs.imports import _NEED_IMPORT_TORCH
  from fastNLP.core.collators import Collator
label_desc: Use image node_id 2 for calling the _MixCollateFn obj's underlying member method code with example usage: obj.__call__(ins_list) and returns: _ins_list